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Search Results: 1 - 10 of 84405 matches for " W Widayat "
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Biodiesel Production from Rubber Seed Oil via Esterification Process
W Widayat,S Suherman
International Journal of Renewable Energy Development (IJRED) , 2012,
Abstract: One promise source of alternative energy is biodiesel from rubber seed oil, because the raw materials available in plentiful quantities and can be renewed. In addition, the rubber seed is still lack of utilization, and Indonesia is one of the largest rubbers producing country in the world. The objective of this research is to studied on biodiesel production by esterification process. Parameters used in this study are the ratio of catalyst and temperature and its influence on the characteristics of the resulting biodiesel product. Characterization of rubber seed include acid content number analysis, saponification numbers, density, viscosity, iodine number, type of free fatty acids and triglyceride oils. The results of analysis showed that rubber seed oil content obtained is 50.5%. The results of the GCMS analysis showed that a free fatty acid level in rubber seed is very high. Conversion into bio-diesel oil is obtained by at most 59.91% and lowest 48.24%.
Potency of Microalgae as Biodiesel Source in Indonesia
H Hadiyanto,W Widayat,Andri Cahyo Kumoro
International Journal of Renewable Energy Development (IJRED) , 2012,
Abstract: Within 20 years, Indonesia should find another energy alternative to substitute current fossil oil. Current use of renewable energy is only 5% and need to be improved up to 17% of our energy mix program. Even though, most of the area in Indonesia is covered by sea, however the utilization of microalgae as biofuel production is still limited. The biodiesel from current sources (Jatropha, palm oil, and sorghum) is still not able to cover all the needs if the fossil oil cannot be explored anymore. In this paper, the potency of microalgae in Indonesia was analysed as the new potential of energy (biodiesel) sources.
Evaluation and Modification of Processes for Bioethanol Separation and Production
Johnner P Sitompul,W Widayat,Tatang H Soerawidjaja
International Journal of Renewable Energy Development (IJRED) , 2012,
Abstract: This paper concerns on process evaluation and modification for bioethanol separation and production by applying pinch technology. Further, the paper is also focused on obtaining a most energy-efficient process among several processes. Three basic process configurations of bioethanol separation and production were selected for this study. The three separations and production systems are Othmer process, Barbet process and a separation process that operates under vacuum condition. Basically, each process is combination of Danish Distilleries process with a separation system yielding 95% (v/v) bioethanol. The production capacity of the plant is estimated about 4 x 107 litre of bioethanol 95% (v/v) per year. The result of the studies shows that the most energy efficient process among the three processes evaluated is the Othmer process, followed by the Barbet process and the process involving vacuum operation. The evaluation also shows that further energy saving can be carried for Barbet and Othmer process configuration when Tmin = 10oC for heat exchange possible.
Diethyl Ether Production Process with Various Catalyst Type
Widayat,Achmad Roesyadi,Muhammad Rachimoellah
International Journal of Science and Engineering , 2013,
Abstract: Several H-zeolite and HZSM-5 catalysts was preparated and their characters have also been investigated. H-zeolit Catalyst was preparated from Natural Zeolite that obtained from Malang District and Gunung Kidul District. Diethyl ether was produced by Ethanol with concentration of 95%. This research use fixed bed reactor that 1 gram of catalyst as bed catalyst, atmospheric pressure and temperature 140oC as the operating condition. Ethanol vapor from vaporization tank was driven by 200 ml/min Nitrogen stream. The responds in this research is liquid product concentration; diethyl ether, ethanol, methanol and water concentration. The results showed that the largest ethanol conversion was produced by the use of 56.44% HZSM-5 and the largest yield of diethyl ether diethyl was produced by the use of alumina and H-zeolite catalyst. The larger ratio between natural zeolite with HCl solvent will produce the larger surface area of catalyst and ethanol conversion. The largest ethanol conversion was produced at reactan ratio 1:20.
. W.
Nieuwe West-Indische Gids , 1951,
Creation of High Energy/Intensity Bremsstrahlung by a Multi-Target and Focusing of the Scattered Electrons by Small-Angle Backscatter at a Cone Wall and a Magnetic Field—Enhancement of the Outcome of Linear Accelerators in Radiotherapy  [PDF]
W. Ulmer
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2013, DOI: 10.4236/ijmpcero.2013.24020
Abstract: The yield of bremsstrahlung (BS) from collisions of fast electrons (energy at least 6 MeV) with a Tungsten target can be significantly improved by exploitation of Tungsten wall scatter in a multi-layered target. A simplified version of a previously developed principle is also able to focus on small angle scattered electrons by a Tungsten wall. It is necessary that the thickness of each Tungsten layer does not exceed 0.04 mm—a thickness of 0.03 mm is suitable for accelerators in medical physics. Further focusing of electrons results from suitable magnetic fields with field strength between 0.5 Tesla and 1.2 Tesla (if the cone with multi-layered targets is rather narrow). Linear accelerators in radiation therapy only need to be focused by wall scatter without further magnetic fields (a standard case: 31 plates with 0.03 mm thickness and 1 mm distance between the plates). We considered three cases with importance in medical physics: A very small cone with an additional magnetic field for focusing (the field diameter at 90 cm depth: 6 cm), a medium cone with an optional magnetic field (field diameter at 90 cm depth: 13 cm) and a broad cone without a magnetic field (
Social Issues of Urban Road Rehabilitation  [PDF]
W. Supul
Current Urban Studies (CUS) , 2018, DOI: 10.4236/cus.2018.63022
This study highlights the social issues of an urban road confronted after the recent rehabilitation works. The study reveals that the road has facilitated faster travel with rider comfort but does not provide a very safe place for residents, children of the kindergarten and school and, walkers. The study has identified several social impacts caused by rehabilitation such as walker and resident un-comfort, inconvenience for businesses, not abating environmental pollution, absence of facilities for disable people and several more. Because the road platform is devoid of trees, the motorists, residents and pedestrians are stripped off of an array of benefits. Nor the road design has considered the comfort of walkers especially disable, elderly, sick and children by not providing a fully connected road walkway and not providing any tree shade and benches to have a rest on a hot and sunny day. The road has also not addressed environmental concerns especially the mechanisms for reduction of impacts of particle and other noxious gases emanating from motor vehicle movement on inhabitants. A method to analyze road impacts is included that serves as an aid for future rehabilitation of urban roads.
On the Origin of Mass and Angular Momentum of Stellar Objects  [PDF]
Peter C. W. Fung, K. W. Wong
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.615235
Abstract: The consequence of the 5D projection theory [1] is extended beyond the Gell-Mann Standard Model for hadrons to cover astronomical objects and galaxies. The proof of Poincare conjecture by Pe-relman’s differential geometrical techniques led us to the consequence that charged massless spinors reside in a 5D void of a galactic core, represented by either an open 5D core or a closed, time frozen, 3D × 1D space structure, embedded in massive structural stellar objects such as stars and planets. The open galactic core is obtained from Ricci Flow mapping. There exist in phase, in plane rotating massless spinors within these void cores, and are responsible for 1) the outward spiral motion of stars in the galaxy in the open core, and 2) self rotations of the massive stellar objects. It is noted that another set of eigen states pertaining to the massless charged spinor pairs rotating out of phase in 1D (out of the 5D manifold) also exist and will generate a relatively weak magnetic field out of the void core. For stars and planets, it forms the intrinsic dipole field. Due to the existence of a homogeneous 5D manifold from which we believe the universe evolves, the angular momentum arising from the rotation of the in-phase spinor pairs is proposed to be counter-balanced by the rotation of the matter in the surrounding Lorentz domain, so as to conserve net zero angular momentum. Explicit expression for this total angular momentum in terms of a number of convergent series is derived for the totally enclosed void case/core, forming in general the structure of a star or a planet. It is shown that the variables/parameters in the Lorentz space-time domain for these stellar objects involve the object’s mass M, the object’s Radius R, period of rotation P, and the 5D void radius Ro, together with the Fermi energy Ef and temperature T of the massless charged spinors residing in the void. We discovered three laws governing the relationships between Ro/R, T, Ef and the angular momentum Iω of such astronomical object of interest, from which we established two distinct regions, which we define as the First and Second Laws for the evolution of the stellar object. The Fermi energy Ef was found to be that of the electron mass, as it is the lightest massive elementary particle that could be created from pure energy in the core. In fact the mid-temperature of the transition region between the
Biopesticides and Their Role in Sustainable Agricultural Production  [PDF]
Geraldin M. W. Lengai, James W. Muthomi
Journal of Biosciences and Medicines (JBM) , 2018, DOI: 10.4236/jbm.2018.66002
Abstract: Biopesticides are derivatives of plants, microorganisms and insects. Substances from plants and animals have been used to manage diseases in crops, animals and humans. Reliance on nature to heal nature is a practise for many people around the world. Use of natural products was overtaken by synthetic chemicals due to their efficacy, reliability and quick knock down effect. However, synthetic pesticides have become a health hazards for humans and environment due to their toxicity and pollution. Biopesticides are potential alternatives to synthetic pesticides. Sources of biopesticides are readily available, easily biodegradable, exhibit various modes of action, are less expensive and have low toxicity to humans and non-target organisms. Neem, pyrethrum, cotton and tobacco are known sources of botanical pesticides and have already been commercialized. Other sources of botanical pesticides include garlic, euphorbia, citrus, pepper among others. Species of Trichoderma, Bacillus, Pseudomonas, Beauveria have been commercialized as microbial pesticides. Biopesticides are however faced with challenges of formulation, registration, commercialization, acceptance and adoption. This paper describes several aspects of biopesticide development, including but not limited to, their sources, production, formulation, commercialization, efficacy and role in sustainable agriculture.
Software Reuse: Developers’ Experiences and Perceptions  [PDF]
William W. Agresti
Journal of Software Engineering and Applications (JSEA) , 2011, DOI: 10.4236/jsea.2011.41006
Abstract: Reusing programs and other artifacts has been shown to be an effective strategy for significant reduction of development costs. This article reports on a survey of 128 developers to explore their experiences and perceptions about using other people’s code: to what extent does the “not invented here” attitude exist? The survey was structured around a novel and simple “4A” model, which is introduced in this article: for an organization to obtain any benefits from reusing code, four conditions must obtain: availability, awareness, accessibility, and acceptability. The greatest impediments to reuse were shown to be awareness of reusable code and developers’ perceptions of its acceptability for use on their new projects. For 72% of developers, the complexity of the old code was cited as a reason that the code was not reused. The survey also included developers’ suggestions for ways to take greater advantage of existing code and related artifacts.
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